Analysis of viscoelastically active polypropylene sutures.

Abstract

By applying a simple thermomechanical treatment to produce viscoelastically active polypropylene surgical sutures, we previously demonstrated that skin cell (fibroblast) motility was positively influenced by viscoelastic recovery mechanisms: these resulted in a progressive lengthwise contraction over a typical 42-day wound healing period and release of electric charges at the suture surface. Nevertheless, two areas have been identified that require investigation to facilitate further developments in this treatment process: (i) to characterise the treatment effect on key suture properties and (ii) evaluate the long-term characteristics of electric charge output from viscoelastic recovery by pursuing an effective detection method, this being achieved through water contact angle measurements (CAMs). For (i), no significant changes in suture tensile strength or thermal properties were found, with only minor differences in other mechanical parameters and surface morphology, these all remaining within the acceptable tolerances of regulatory bodies. For (ii), CAMs showed the treatment produced significant time-dependent reductions in suture hydrophobicity. Direct correlation was observed between contact angle and skin cell motility data, demonstrating that the CAMs method provides a sensitive, time-resolved measure of changes to surface properties during viscoelastic recovery. The CAMs data complement the findings of the previous electrometer-based method, whilst overcoming the sensitivity and time-detection limitations. The CAMS technique is expected to give greater insight into mechanisms occurring during viscoelastic recovery and provides a valuable preliminary indication of potential cellular response prior to future in-vitro experiments. By inducing time-dependent cellular responses linked to measurable changes in suture surface characteristics, the thermomechanical treatment offers a promising pathway for developing next-generation surgical sutures.